Abstract Body

Background: Exercise in type 1 diabetes (T1D) remains challenging. Intensity and duration impact glucose levels but this varies with exercise type. Separating increased glucose uptake due to muscle action from increased insulin effectiveness allows us to model glucose changes and better adjust insulin delivery.

Methods: Participants with T1D performed aerobic (n = 26) and resistance exercise (n = 25) during two clamp studies to obtain rate of appearance (Ra) and disappearance (Rd) of glucose. Participants were divided into 2 cohorts, moderate and intense exercise, and engaged in three experiments at different, constant insulin infusion rates (basal, 1.5* basal, and 3*basal). A model of glucose dynamics estimated Ra and Rd, and linear regression across the three experiments per participant obtained insulin-mediated effect. Non-insulin mediated effect was the intercept. We determined area under the curve for endogenous glucose production (AUC_EGP) and Rd (AUC_Rd) over 45 min of exercise.

Results: During aerobic exercise, AUC_Rd increased 12.45 mmol/L and 13.13 mmol/L (P < 0.001) whereas AUC_EGP increased 1.66 mmol/L and 3.46 mmol/L (P < 0.001) above baseline during moderate and intense exercise, respectively. AUC_EGP increased during intense exercise by 2.14 mmol/L (P < 0.001) compared with moderate exercise. Insulin-mediated glucose uptake rose during exercise and persisted hours afterward, whereas non-insulin-mediated effect was limited to the exercise period (figure 1). Preliminary data from resistance exercise is shown in Figure 2.

Conclusions: Separating insulin and non-insulin glucose uptake during exercise in T1D has not been done before. This method allows visualization of these changes for the first time.